I have a Ultra 155 boiler with an indirect 40 gal DWH. 4 zones, plus prioritized domestic water Taco switching relay. The system uses 4 taco cartridge circulators for the four zones plus one for the DWH. It constantly goes off (at least once every other week in the winter) on a too much flow warning and has to be manually reset. What can be done to prevent this from happening? Why doesn't it reset itself?

Did you check this yet?

Ultra 155 & 230 Gas Boilers Recalled by Weil-McLain


Here is your manual I believe

http://www.weil-mclain.com/en/multim...ler_manual.pdf

All flow levels should have been calculated by the heating engineer before the install.

The problem you are having could be caused by a number of different items and sorry to say but my time here is limited and a true on site inspection actually needs to be done to get a overall feeling for the system you have.. I have provided you with the factory manual just in case you do not have one and I suggest you start from the beginning and read it or contact the company that sold and installed you the equipment. While condensing boilers are a good thing problems do creep up usually sooner than later. Good luck.

This is a residential install, I don't believe it is necessary to be that specific with the gpm through each zone, and it does not happen each time all four zones are callling for heat. All circs are turned to the slowest of the three speeds. I think it is a glitch in the computer module, I will investigate further, and update you. The primary loop circulator determines flow for the readout anyway doesn't it?

The boiler does not know where it is installed. Boilers are getting smarter but I doubt if they know the difference between a commercial structure or residential structure since the boiler operation is the same.